Spiral Welded Steel Pipe

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Spiral Welded Steel Pipe

The spiral welded steel pipe is manufactured using hot rolled steel strip which is spiraled at room temperature to be welded. Automatic submerged arc welding is the most commonly used method in the spiral tube production, and the end products come with welding seam both inside and outside.

With an annual production capacity of 250,000 tons, we can supply this tube with diameters between 219mm and 3000mm and thickness between 4mm and 25mm, according to customer's request. We can make 3PE coating, epoxy resin coating, and black paint coating for spiral pipes. Our anti rust coating is of good quality. All our products are manufactured in accordance with ASTMA53, ASTMA252, API5C, GB/T9711.1, or GB/T9711.2 standards. Our spiral welded steel pipe is ideal for transportation of natural gas, water, coal gas, heating steam, and so on. It can also be applied in piling or steel structure construction fields.

1. Raw Material Inspection
2. Uncoiling
3. Rough Leveling
4. End Cutting and Butt Welding
5. Precision Leveling
6. Delivering
7. Forming By Inner and Outer Welding
8. Welding Slag Cleaning & Overall Inspection
9. repair Welding, X-Ray Inspection, Scanning, And Re-Inspection By Manual UT
10. Chamfering
11. Hydrostatic Testing
12. auto Length-Measuring and Weighing
13. Coating and Marking
14. storage

Welding Connection

1. Place the two pipes to be connected on the same flat surface and keep them coaxial.
2. Keep the liner between the two pipe ends.
3. Be sure the bevel angle is qualified. Our spiral welded steel tubes offer standard bevel angle between 30° and 35°. For products with other bevel angles, please specify in the order contract.
4. In 30 minutes after welding, don't move the welded tubes to avoid welding cracks.
5. In 24 hours after welding, we don't recommend conducting nondestructive testing. If the testing is very urgent, it should be performed at least 12 hours after welding. Because some welding defects occur during welding line cooling process, and thus cannot be detected immediately.

Flanged Connection

1. Be sure the flange fittings are accurately positioned and parallel to each other. Meanwhile, be sure they are perpendicular to the spiral welded steel pipe's center line.
2. Use bolts with the same specifications for flange fastening. The bolts' mounting directions should be the same, and the bolts should be symmetrically mounted. After fastening, be sure there are bolt threads protruding beyond the nut. At least, the nut should be fully threaded onto the bolt. We recommend using galvanized nuts to avoid corrosion.
3. While fastening using bolts and nuts, please make sure there is no axial tension generated by the pipes.
4. A supporting bracket should be available at the flange connected positions.

Installation Troubleshooting
When there is a large diameter difference between the two pipes causing butt welding quality problems, please do as the following listed.

1. Check whether the tube diameter and ovality are up to standard.
Clients only need to measure the tube circumference and pipe end diameter, and send the data to us. If any one of the data is unqualified, we will negotiate with our client to solve the problem. If the data are up to standard, clients have to rotate one of the tubes to a position that allows for optimum quality welding. The optimum position makes sure the size difference is not over 3mm which won't cause welding quality problems.

2. Check whether the bevel cutting for the spiral welded steel pipes is up to standard.
If possible, please measure the data and send to us. If the bevel cutting is unqualified, we will negotiate with clients to solve the problem. If the bevel cutting is qualified, please rotate one of the pipes to make sure the maximum gap between the edges is not more than 2mm, so as to assure quality welding.

3. Pipe end remanence
Use a magnetometer to measure the magnetic intensity. Magnetic flux density at the pipe ends lower than 40×10-4T won't cause welding quality problems. If the value exceeds 40×10-4T, clients have to take measures to eliminate the residual magnetism at the ends of the spiral welded steel pipe.

There are two commonly used residual magnetism elimination methods.
(1) Use an angle grinder to grind the inner pipe wall at the pipe end. One-time grinding in anticlockwise direction will effectively eliminate the residual magnetism.
(2) Wind a 20mm² electrical wire in clockwise direction on the pipe end, and the minimum coil number is not less than 10 coils. Then connect the two ends of the electrical wire to a DC welding machine, and keep the current at about 200A. Watch the electrical wire temperature in the following 20 minutes, and meanwhile, prepare three iron wires with the same diameter of 3mm, and with lengths of 120mm, 50mm and 20mm respectively.
After that, check whether the iron wires can be attracted by the pipe end sections. As long as the iron wire with lengths of 120mm and 50mm cannot be attracted, clients can perform pipe welding as usual. If iron wire with 20mm length cannot be attracted either, it proves that the residual magnetism has been completed eliminated.
No indication of magnetic intensity reduction is usually caused by reversed connection of the DC power supply. Be sure the power supply is correctly connected, and then repeat the above procedures to eliminate the magnetic intensity at the ends of the spiral steel pipe.

Packaging, Transportation, and Storage
1. Lifting Instructions
The lateral contact surface between the lifting hook and the pipe end is not supposed to less than 40mm. Or else, the pipe end may be deformed, which may cause welding problems.
During lifting transportation, at most 4-5 spiral welded steel pipes with diameter of 219mm, 273mm, 325mm, or 377mm can be lifted synchronously; at most 2-3 pieces for that with diameters of 426mm, 478mm, or 529mm at a time; and at most 2 pieces for that with diameters of 630mm or 720mm. Tubes with diameter of 820mm or above have to be lifted one by one.

2. Transportation Instructions
During transportation, please avoid impact among tubes as well as the impact between tubes and other hard objects, so as to avoid deformation of the pipe end or pipe body. Impacts may also cause scratching on the pipe body.

3. Storage Instructions

(1) Overhigh stack height may cause product deformation. Hence, the maximum stack layer is 2 layers, as for spiral welded steel pipe with diameter of 1220mm or above, as well as diameter and wall thickness ratio higher than 150; and 3 layers for products with diameter between 820mm and 1020mm.
(2) In order to avoid corrosion, the spiral tubes should be protected by waterproof cloth to keep away from corrosive liquid, gases, as well as factories manufacturing corrosive substances.
(3) Never place the products on ground directly, so as to avoid pipes at the bottom layer dipping into water in bad weather conditions.
(4) Clamps should be utilized to fix the stacked welded pipes so as to avoid accidents caused by falling down of tubes at the top layers.

Technical Specifications
Size Range: 8 "~118'' (219~3000mm)
Wall Thickness: 4~25mm
Standard: ASTM A53, ASTM A252, API 5C, GB/T 9711.1, GB/T9711.2
Steel Grade: Q235, Q345B, GR.B, X42, X46, X52, X56, X60, X65
End Finish: Plain end, bevel end
Pipe Coating: Bare pipe, black vanish or 3PE coating, epoxy coating.

Related Names
Spiral Welded Steel Tube | Spiral Welded Steel Pipe